It is well known that, as opposed to laparotomy, minimally invasive medical procedures have the benefit of reducing the amount of extraneous tissue that is damaged during diagnostic or surgical procedures. This results in shorter patient recovery time, less discomfort and deleterious side effects, and lower costs of the hospital stay. Nowadays, in general surgery, urology, gynecology and cardiology specialties, there is an increase of the amount of surgical operations carried out by minimally invasive techniques, such as laparoscopic techniques.
Minimally invasive techniques in general and laparoscopy in particular do however put more stringent requirements on the surgeon carrying out the operation. The surgeon operates in an uncomfortable and tiring posture, with a limited field of view, reduced freedom of motion and poor tactile perception. To these problems adds the fact that surgeons often have to carry out several consecutive interventions per day, each intervention lasting e.g. from 30 minutes to several hours. In spite of these difficulties, the trend towards minimally invasive procedures is probably going to increase sharply in the coming years due to the ageing population and the pressure of costs in the medical field.
In laparoscopy the surgeon is obviously required to be as precise in his moves as in laparotomy. Manipulating long-shaft instruments with motion dexterity reduced to four degrees of freedom about a fulcrum at the instrument access port, i.e. at the incision in the patient body, is not alleviating this task. Complications arise inter alia by the fact that the required posture is quite tiresome and reduces the already limited perception of interacting forces between instrument and tissues. For example, when the surgeon stands aside the patient, he must lift and maintain stretched one of his arms to hold the instrument inserted at the opposite side of the patient. As a result, motorial capabilities of the surgeon decay normally after 20-30 minutes, such that among others trembling, loss of accuracy and loss of tactile sensitivity occur with the resulting risks for the patient. Therefore, new technologies, such as robotically assisted laparoscopy, are emerging which aim at improving efficiency, quality and safety of interventions.
In view of the above, robotically assisted laparoscopy has known significant development since the early nineties. Two representative commercially available robotic surgery systems are the surgery system known by the trademark ‘DA VINCI’ developed by Intuitive Surgical Inc., Sunnyvale, Calif. and the surgery system known by the trademark ‘ZEUS’ originally developed by Computer Motion Inc., Goleta, Calif. The surgery system known by the name ‘DA VINCI’ is described among others by Moll et al. in U.S. Pat. No. 6,659,939; U.S. Pat. No. 6,837,883 and other patent documents of the same assignee. The surgery system known by the name ‘ZEUS’ is described among others by Wang et al. in U.S. Pat. No. 6,102,850; U.S. Pat. No. 5,855,583; U.S. Pat. No. 5,762,458; U.S. Pat. No. 5,515,478 and other patent documents assigned to Computer Motion Inc., Goleta, Calif.
These tele-operated robotic systems permit to control surgical interventions either directly from the operation theatre or from a remote site, using visual feed-back on a console. In either case, the tiring posture of the surgeon is eliminated.
Apart from the high purchase and maintenance costs of these robotics systems, their diffusion and acceptance in the medical community is limited among others because of a lack of versatility. Both systems were designed specifically for cardiologic surgery where the topological anatomy is constant, the workspace is small and therefore accurate instrument motion and dexterity are required in a limited space only. Accordingly, the mechanical design of these systems is not readily suitable for use in other types of surgery (including gynaecology, urology and general surgery) where the operating workspace is larger than in cardiology, the anatomical topology is variable (even sometimes unpredictable), and the mechanical properties of tissues and organs are diverse.
Irrespective of these two specific systems, the mechanical design of manipulators in robotic surgery systems currently leaves significant room for improvement in various aspects among which versatility of the system is but one of many.